[ovs-dev] [PATCHv3] netlink: added check to prevent netlink attribute overflow

[Cpp Code]

> On 20 Feb 2019, at 02:27, Gregory Rose <gvrose8192 at gmail.com> wrote:
> 
> 
> On 2/19/2019 10:55 AM, Toms Atteka wrote:
>> If enough large input is passed to odp_actions_from_string it can
>> cause netlink attribute to overflow.
>> Check for buffer size was added to prevent entering this function
>> and returning appropriate error code.
>> 
>> Basic manual testing was performed.
>> 
>> Reported-by:
>> https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12231 <https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12231>
>> Signed-off-by: Toms Atteka <cpp.code.lv at gmail.com> <mailto:cpp.code.lv at gmail.com>
>> ---
>>  lib/odp-util.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>> 
>> diff --git a/lib/odp-util.c b/lib/odp-util.c
>> index e893f46..e288ae8 100644
>> --- a/lib/odp-util.c
>> +++ b/lib/odp-util.c
>> @@ -2161,6 +2161,10 @@ parse_action_list(const char *s, const struct simap *port_names,
>>          n += retval;
>>      }
>>  
>> +    if (actions->size > UINT16_MAX) {
>> +        return -EFBIG;
>> +    }
>> +
>>      return n;
>>  }
>>  
> Hi Toms,
> 
> Thanks for the patch.  Question though, why EFBIG instead of E2BIG?  This would appear to be a situation in
> which too many arguments are sent (E2BIG) but then maybe it is from a file (EFBIG)?
> 
> Also, I see this is a version 3 of this patch?  What changed from version 1 to version 3?  Commonly the
> changes from each version of a patch are posted beneath the git separator '---'.  Like below...
> 
> Thanks,
> 
> - Greg
> 
> Signed-off-by: Martin Xu <martinxu9.ovs at gmail.com> <mailto:martinxu9.ovs at gmail.com>
> CC: Flavio Leitner <fbl at sysclose.org> <mailto:martinxu9.ovs at gmail.com>
> CC: Yi-Hung Wei <yihung.wei at gmail.com> <mailto:yihung.wei at gmail.com>
> CC: Yifeng Sun <pkusunyifeng at gmail.com> <mailto:pkusunyifeng at gmail.com>
> CC: Zak Whittington <zwhitt.vmware at gmail.com> <mailto:zwhitt.vmware at gmail.com>
> CC: Ben Pfaff <blp at ovn.org> <mailto:blp at ovn.org>
> ---
> v1->v2: adds "Obsoletes" tag needed for upgrade after renaming
>         adds more reviewers
> 
> 

Hi Greg, 


Thats not a case of too many arguments provided, but the the size of a single argument is too large, so I believe EFBIG is more appropriate.

I guess its not worth creating v4 but ill keep in my mind off adding change log next time.

Thanks,
Tom